In article , AnonLinuxUser
wrote:

Well, you definitely did the research. Wife did have a step wave UPS,
and the iMac started doing some strange things, (like emptying trash
that doesn't empty the trash and hang). Got her a pure sine wave UPS
and those problems disappeared.

unrelated and a coincidence.


Not a coincidence if you know your electronics well enough.

i do, and it is very much a coincidence. stepped sine waves won't cause
the trash not to empty.


The UPS stepped output can cause harmonics that the iMac power supply
can't handle. I put a new UPS pure wave output and the problem went away.

false. imacs have no issue with stepped sine waves, nor do other macs.

But not in my case. Is it a faulty ps in the iMac? Could be, but the
pure sine wave output is a much better options.

pure sine wave is better but it cannot cause the symptoms you describe.

Whether you put much
trust in the GeekSquad or not, they did say that some iMacs are affected
by this.

geeksquad? seriously?

So I went up to another store and asked the same question.
Funny that the store won't stock the cheap stepped UPS, but they do
stock the better ones.

that means nothing.

you also shouldn't be running anything off a ups for an extended period
of time anyway. it's for brief amounts of time, to safely shut down.


The UPS has about 2 hours of power before I have to shut down the iMac.

higher end upses that last that long normally are pure sinewave.

that said, i've run several different macs, pcs, upses and many other
devices for 30+ minutes off a cheap ups (stepped sine) without issue.


But not her iMac. It is not fun to have a hanging process. You have
to, in this instance, bring up Activity Monitor and force quit Finder.
Which, in this case, also mandates a restart.

no it definitely doesn't require a restart, nor is activity monitor
needed to force quit finder.